But, really, at what point does it become not worthwhile to fight an insurgency anymore?
I'm not talking about Afghanistan here. Thailand has been fighting (off and on) an insurgency in its extreme southern provinces (which are Muslim and Malay, instead of Buddhist and Thai) for about a century now. Today, the security forces raided a school due to concerns about indoctrination into insurgency there.
And it seems they came up with something. There were in fact books on how to be suicide bombers, and they are interrogating 60 students. It could represent a real breakthrough, but I'm very skeptical.
It is said that insurgency is a long slog and very difficult to do. What does Thailand gain by keeping these three provinces? It is not like the separatism would spread to the rest of Thailand; these provinces are unique in many ways in Thailand. These are the only places that are majority Muslim or majority Malay. In fact, this is a former independent country that then-Siam annexed in the early 20th century. It is not like other provinces would be encouraged to do the same thing (unlike China).
I do not know what, other than pride, Thailand gets out of continuing to hold these provinces. However, no one ever wants to give up and accept that losing sometimes is less costly than winning.